Ryu sits next to 3 phonetic neighbors — Drew, Lew, and Rue are the closest matches by sound. Most share Ryu's Japanese cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"flow, current, stream"
"oracle, mouth of the serpent"
"winding valley"
"invented modern name"
"dove, peaceful one"
"God has seen"
"ancestor of northern Arab tribes"
"of Dionysus, god of wine"
"graciousness, kindness"
"coined name; possibly edge-land dweller (via Kent)"
"spear, acquired"
"my God has helped"
"certificate of authenticity"
"God is gracious"
"coal farm"
"young male horse"
"from the heath"
"son of Ky (invented)"
"the brave ones, the warriors"
"to conquer, to win"
"shortened form of Aristotle: best purpose"
Similar sound: These names share phonetic patterns with Ryu — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Japanese origins, giving them the same cultural heritage as Ryu.
Rhythm: Ryu is a 1-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.